1. Field of the Invention
The invention relates generally to novel micro-column designs for micro-gas chromatography (μGC) micro-columns, such as serpentine micro-columns, which give relatively lower height equivalent to theoretical plate (HETP) values. Turns are a major dispersion source for serpentine configuration and sinusoidal compensation structures following the turns may result in the lowest dispersion.
2. Related Art
A gas chromatograph (GC) is a chemical analysis instrument used for separating chemicals in a complex sample and is generally composed of three basic parts, an injector, a column, and a detector. Different chemical constituents of a sample pass in a gas stream through the column at different rates depending on their various chemical and physical properties and their interaction with a specific column filling, called the stationary phase. As the chemicals exit the end of the column, they are detected and identified electronically. Conventional GC columns are generally small open tubes with internal diameters in the range of about 270 microns to about 530 microns and lengths bout in the range of about 10 meters to 30 meters. The inside walls of these columns are coated with a thin even layer of organic polymer, the stationary phase, to a thickness of less than about one micron.
Conventional GCs are very bulky and are not small enough to be carried by individuals. Therefore, many efforts are being made to develop a GC that is highly miniaturized and portable, a so-called microfabricated GC (μGC). Micro-columns are the heart of the GC technique and several studies have considered microelectromechanical systems (MEMS) columns for μGC's. Previous work on μGC, however, has concentrated on columns that are arranged with a spiral geometry as shown in FIG. 1, Panel A. Research done by applicants indicates that the spiral channel configuration may not be well suited for microanalytical system, as discussed below.
Therefore, a need remains for a microfabricated GC column that minimizes band broadening, enables long column lengths with low pressure drop, enables uniform stationary phase coatings, and provides a column configuration that can be easily integrated with other microfabricated components to provide a compact and fast microanalytical system.